Resin pipes made of polyethylene, polypropylene, polybutene, polyvinyl chloride, etc. have widely been used as fluid-conveying pipes such as gas pipes, running water pipes, etc. There are various methods for connecting these resin pipes, and the most widely used method is a type in which a nut is screwed to a joint body, a mechanical connecting method comprising mounting a locking ring member and a packing between the joint body and the nut, and screwing the nut with a wrench to compress the locking ring member and the packing to achieve sealing.
However, the above mechanically connectable pipe joint is disadvantageous in that it is impossible to confirm after the fastening operation whether or not the pipe is fully inserted into the pipe joint, and that it is also difficult to confirm how tight the nut is fastened, resulting in unevenness in the performance of the pipe connection. The confirmation of how well the pipe joint is connected is only a leak test after the fastening operation. Even if the connected pipe joint has passed the leak test conducted for a short period of time after the fastening operation, the detachment of the pipe from the pipe joint and leak are likely to take place during a long period of use.